In the past, a system for controlling/monitoring equipments connected to a non-IP network by a terminal device connected to an IPv6 network has been proposed. This system has a gateway for enabling communication between the equipments for the non-IP network and the terminal device for the IPv6 network by acquiring identification information and interface IDs of the equipments used in the non-IP network as well as network IDs used in the IPv6 network, generating IPv6 addresses from these IDs, and managing a correspondence between the generated addresses and the identification information. By use of this gateway, the terminal device can control or monitor the equipments.
For example, this kind of network system is disclosed in Japanese Patent Early Publication No. 2003-60664. In this system using non-IPv6 equipments, a terminal device for an IPv6 network sends a packet with a header including destination IPv6 address. In a gateway, an IPv6 address is allocated to a non-IPv6 equipment. Therefore, when the terminal device accesses plural equipments, it becomes necessary to generate the IPv6 address corresponding to each of the equipments. Thus, it is needed to take account of the IPv6 address. In addition, even when increasing the number of the equipments for performing the same operation, another IPv6 address corresponding to the added equipment becomes necessary. Therefore, there are inconveniences that the plural equipments cannot be controlled or monitored by use of a single identifier, and plural identifiers cannot be allocated to a single equipment. Furthermore, it is not possible to flexibly cope with an increase in the number of the equipments for providing services.